They were jailed for "belonging to a forbidden political party which wants to amputate part of Syrian territory to annex it to a foreign state," the Syrian Organisation for the Defence of Human Rights (SODH) announced.

Jihad Saleh Abdo, 42, and Abdel Qader bin Sido Ahmad, 35, who both faced additional charges of "weakening national sentiment" and "inciting racial disagreements," were each sentenced on Sunday to five years in prison, it said.

Saleh bin Mohammed Abdo, 32, and Hussein bin Hamid Mohammed, 29, received four-year terms, the SODH said.

The four members of the banned Azadi party were arrested in September 2007 at Afrin in the Aleppo region of northern Syria and held in Saydnaya prison near Damascus.

There is no appeal against judgments by the state security court.

"The state security court does not allow prisoners to appeal, constituting a breach of the right to a fair trial. We call on the Syrian government to close it down, cancel all its judgments and take rapid steps for the respect of all rights," the SODH said.